Cosmic Ray Driven Outflows from the Large Magellanic Cloud: Contributions to the LMC Filament

TL;DR

This study uses simulations to investigate cosmic ray-driven outflows from the Large Magellanic Cloud, examining their contribution to the Magellanic Stream and the effects of ram pressure, star formation history, and magnetic fields.

Contribution

It presents the first simulations incorporating the LMC's star formation history to model cosmic ray-driven outflows and their impact on the Magellanic Stream.

Findings

Outflows contribute minimally to the Magellanic Stream mass.

Ram pressure significantly influences halo gas distribution.

Absorption studies may underestimate the total halo mass.

Abstract

In this paper, we build from previous work (Bustard et al. 2018) and present simulations of recent (within the past Gyr), magnetized, cosmic ray driven outflows from the Large Magellanic Cloud (LMC), including our first attempts to explicitly use the derived star formation history of the LMC to seed outflow generation. We run a parameter set of simulations for different LMC gas masses and cosmic ray transport treatments, and we make preliminary comparisons to published outflow flux estimates, neutral and ionized hydrogen observations, and Faraday rotation measure maps. We additionally report on the gas mass that becomes unbound from the LMC disk and swept by ram pressure into the Trailing Magellanic Stream. We find that, even for our largest outburst, the mass contribution to the Stream is still quite small, as much of the outflow-turned-halo gas is shielded on the LMC's far-side due to the LMC's primarily face-on infall through the Milky Way halo over the past Gyr. On the LMC's near-side, past outflows have fought an uphill battle against ram pressure, with near-side halo mass being at least a factor of a few smaller than the far-side. Absorption line studies probing only the LMC foreground, then, may be severely underestimating the total mass of the LMC halo formed by outflows.